add method to validator containers to retrieve all child validators
update all xsds to allow a <sandbox> block as the first child of the <configurations> block
made plural parent tag optional in more places (this should be all places where its possible to do now)
fixed output type detection in execution time and form population filters
allow layers to be omitted and make output_types obligatory again
make the validator name attribute optional
added export possibilities to equals validator
make validators only throw their errors once when there are multiple arguments and they arent't set
reverted 19ba14ef32a6735fd093fcb9c8402d8cddf199d0
filter out <sandbox> elements in XML config parser
fixed phpdoc
ZE WRONG TYPE, ZE WRONG TYPE